Smail-Crevier Rachel L, Maracle Amanda C, Wash Sarah I J, Olmstead Mary C
Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Department of Psychology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Physiol Behav. 2018 Oct 1;194:420-429. doi: 10.1016/j.physbeh.2018.06.027. Epub 2018 Jun 23.
Binge eating disorder is the most common eating disorder, but its underlying etiology is poorly understood. Both humans and animals exhibit binge-like intake of highly-palatable food, suggesting that the behavior is driven by the rewarding properties of food, rather than homeostatic signals. Food reward is regulated, in part, by endogenous opioid mechanisms which, themselves, may be altered by excessive eating. We examined this hypothesis by testing whether binge-like sucrose intake modifies the subsequent development of a conditioned place preference (CPP) to sucrose and morphine in both female and male adult rats. Separate groups were given intermittent (12h) or continuous (24 h) access to a sweet solution (10% sucrose or 0.1% saccharin) and food in their home cage over 28 days. Intermittent sucrose access induced binge-like intake, defined as increased consumption within the first hour; importantly, daily sucrose intake was similar for continuous and intermittent access groups. In a later test, all rats developed a conditioned place preference (CPP) to 15% sucrose with the exception of female and male rats given 12-h intermittent access to sucrose. In a separate experiment, all groups displayed a CPP to morphine (4 mg/kg). These findings demonstrate that binge-like sucrose intake, not just increased consumption, disrupts reward processing without affecting stimulus-reward learning. This fits with clinical evidence of hypo-reward responsivity in patients with binge eating disorder.
暴饮暴食症是最常见的饮食失调症，但其潜在病因却鲜为人知。人类和动物都会出现对美味食物的类似暴饮暴食的摄入行为，这表明这种行为是由食物的奖励特性驱动的，而非体内平衡信号。食物奖励部分受内源性阿片类机制调节，而这种机制本身可能会因过度进食而改变。我们通过测试成年雌性和雄性大鼠类似暴饮暴食的蔗糖摄入是否会改变随后对蔗糖和吗啡的条件性位置偏爱（CPP）的发展来检验这一假设。在28天内，将不同组的大鼠分别间歇性（12小时）或持续性（24小时）地放入其笼舍中接触一种甜味溶液（10%蔗糖或0.1%糖精）和食物。间歇性蔗糖接触会引发类似暴饮暴食的摄入行为，定义为在第一小时内摄入量增加；重要的是，持续性和间歇性接触组的每日蔗糖摄入量相似。在随后的测试中，除了给予12小时间歇性蔗糖接触的雌性和雄性大鼠外，所有大鼠都对15%的蔗糖产生了条件性位置偏爱。在另一项实验中，所有组的大鼠都对吗啡（4毫克/千克）产生了条件性位置偏爱。这些发现表明，类似暴饮暴食的蔗糖摄入，而非仅仅是摄入量增加，会扰乱奖励处理过程，而不影响刺激-奖励学习。这与暴饮暴食症患者奖励反应性降低的临床证据相符。
